Thyme keeps on Dying

I live in the inner parts of southern California...so I would say a zone 9. With summer temperatures averaging in the mid 90 degrees. I buy pregrown German/French thyme from Home Depot and often transplant it to a pot on the same day. The soil is definitely well drained.
I have tried several scenarios:
1) part shade and water every 3 days
2) full sun and every 3 days
3) part shade water once a week
4) full sun water everyday
All scenarios ended with the death of the thyme. I am at my wits end. Rosemary, Basil, and Oregano seem to always survive but the thyme just starts wilting then dies. Is it perhaps the transplanting that is hurting the thyme? I don't break the roots. What am I doing wrong?

Repotting can weaken plants for a few days while they are adjusting, so it's best to not give them full sun until a few days later.

You may also want to find a new supplier. Since the thyme bought from the same store always dies, maybe there is a disease problem or the plants are just poorly cared for. Thyme can also be grown from seed.